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Fraction foundations · Lesson 1 of 3

What is a fraction?

Start with one whole. Split it into equal parts and give those parts a name.

Explore it

Build a fraction.

Choose how many equal parts make one whole. Tap a part to shade or unshade it.

One whole

3 shaded parts
out of 4 equal parts in all.

The whole stays the same size. Changing the number of equal parts changes the size of each part.

Look a little closer

Read the two numbers.

Imagine one whole bar split into 4 equal parts, with 3 shaded. We write 3/4, and say “three fourths.”

3 · Numerator
The top number tells us how many parts are shaded.
4 · Denominator
The bottom number tells us how many equal parts make the whole.

Equal size matters. Four unequal pieces do not each represent one fourth of the whole.

Give the idea a try.

Take your time. Each answer comes with an explanation, and you can try again.

Think it through · 1A bar has 6 equal parts. You shade 2. What fraction is shaded?
Think it through · 2A sandwich is cut into 4 unequal pieces. Is each piece one fourth of the sandwich?

Ready to use it?

Try fresh questions on this idea, or keep exploring the series.

Next lesson: Fractions on a number line